# 输出二维数组
def show2d(b):
    for i in range(len(b)):
        for j in range(len(b[i])):
            print(b[i][j], end=" ")
        print()


# 创建一个二维数组 长度为row 宽度为col
def create2d(row, col):
    b = []
    for i in range(row):
        b.append(list([0] * col))
    return b


b = create2d(3, 4)
show2d(b)
